Thanks to Paul Froehlich for the tip, here's a good article in The Atlantic from a Dean pollster (Paul Maslin) on how the campaign fell from front-runner to third-place.
I think they overstate the "problem" of young, out-of-state Dean campaigners in Iowa -- 3500 young volunteers is an asset, not a liability. Looks like my experience in Dubuque with the Kerry campaign fits with this narrative, as the Kerry campaign ran a traditional 'knock on doors, identify your core supporters and get them out to vote (or caucus)' while Dean didn't do that.
With 3500 volunteers, the Dean campaign could have had a precinct captain in every single precinct. And I think people respect a knock on the door (especially in the winter) more than a phone call from regional headquarters. Maybe the Dean campaign should have assigned each out-of-state volunteer to a precinct and had them walk every day. That walking also tends to instill a sense of humility and deference, which also plays well with older voters.